PROJECT SUMMARY/ABSTRACT The Affordable Care Act (ACA) has special implications for behavioral health, through expanded coverage, legislative mandates specific to behavioral health, and behavioral health parity with medical and surgical benefits. These changes to behavioral health coverage have the potential to shift the treatment landscape for mental health and substance use disorders. Behavioral health benefits are critical to HIV+ individuals, because mental health and substance use disorders are highly prevalent. Untreated substance use and psychiatric disorders have both been associated with poor general and HIV-related health outcomes and with increased population-level transmission of HIV. In addition, mental health conditions are often co-morbid with substance use disorders. Consequently, developing an evidence base for behavioral health will have implications for policymakers seeking to ensure availability of appropriate care for two, often strongly comorbid, groups of treatable conditions. Few studies have examined the effects of the ACA on the health outcomes of people with HIV, and there are no studies on changes in their behavioral health and ACA implementation. The overarching objective of this study is to estimate and interpret the effects of the ACA on behavioral health service utilization and behavioral health outcomes in people with HIV. The quantitative component of this study will estimate the effects of ACA implementation on mental health and corresponding treatment, with a focus on depressive symptoms, in addition to substance use disorders, examining alcohol use, illicit drug use, and associated treatment. Finally, the aims of this study include a qualitative component, which is also the focus of the proposed training plan. The qualitative aim will assess awareness and perception of the ACA's effects on behavioral health coverage and care by conducting in-depth interviews with people with HIV and behavioral health needs. This mixed-methods approach leverages the quantitative data from two longitudinal studies of HIV infection with in-depth interviews with a subset of HIV+ study participants to estimate and interpret behavioral health trends. This study will be the first to examine the effects of the ACA on the behavioral health of people with HIV and will contribute to a nuanced evidence base of the shifting behavioral health services landscape, the behavioral health needs of people with HIV, and remaining barriers to behavioral health care. These aims align with AHRQ funding priorities in that they will examine changing access to behavioral health care and associated health outcomes in a priority population of people with HIV who have behavioral health needs. In addition to the research aims, this project will provide me with the training and mentorship to apply mixed methods approaches to new questions on policy and health insurance in people with HIV. I am confident that the research project, training, and mentorship that I will receive under this fellowship will position me to submit a K series award, to continue studying the effects of health policies on vulnerable populations.